| 摘要 |
An exhaust purification system in which when an air-fuel ratio of exhaust gas is leaner than a stoichiometric air-fuel ratio, a silver-alumina-based catalyst device releases adsorbed NO2 at a first set temperature and releases adsorbed NO at a second set temperature which is lower than the first set temperature. When the air-fuel ratio of the exhaust gas is leaner than the stoichiometric air-fuel ratio and the silver-alumina-based catalyst device is a third set temperature which is lower than the second set temperature, a temperature rise of the silver-alumina-based catalyst device is suppressed to maintain the silver-alumina-based catalyst device near the third set temperature, and at least part of the NO which is adsorbed at the silver-alumina-based catalyst device is oxidized to NO2 to be adsorbed at the silver-alumina-based catalyst device, then the suppression of the temperature rise of the silver-alumina-based catalyst device is lifted. |
